Stapled peptides inhibited HIF-1α/p300 interaction more potently by enhancing helix formation during binding rather than in solution — challenging a core assumption in peptide drug design.
Bound-state helixnot solution-state pre-organization, explains why stapled peptides are more potent — challenging a core assumption in peptide drug design
What the researchers found
The standard assumption in peptide drug design is that stapling peptides into a helix in solution (the unbound state) makes them better drugs because they are pre-organized for binding. This study challenges that assumption.
Stapled peptides derived from HIF-1alpha were indeed more potent inhibitors of the HIF-1alpha/p300 protein-protein interaction. But circular dichroism (CD) spectroscopy showed they were not significantly more helical than unstapled versions when free in solution.
Molecular dynamics simulations and CD difference spectra revealed the real mechanism: stapling helped the peptides adopt the bioactive alpha-helical conformation specifically when bound to p300. The staple does not lock the helix beforehand; it enables better helix formation at the moment of binding.
This finding shifts the design paradigm: optimizing for bound-state helicity, not free-state helicity, is what matters for stapled peptide inhibitors.
Why it matters
Protein-protein interactions drive cancer, inflammation, and many diseases but are notoriously hard to drug with small molecules. Stapled peptides are a leading strategy to fill this gap. This study corrects a widespread design assumption, potentially improving how the field creates next-generation stapled peptide drugs.
The numbers in context
Dibromomaleimide stapling; improved potency; no change in unbound helicity; bound-state helix confirmed by CD and MD
How the study worked
Peptides derived from HIF-1alpha were synthesized with and without dibromomaleimide staples. Binding potency was measured using competition assays against the HIF-1alpha/p300 interaction. Circular dichroism characterized secondary structure in unbound and bound states. Molecular dynamics simulations modeled conformational behavior.
Who was studied
Synthetic peptides and purified proteins (in vitro biophysics)
What this study cannot tell us
In vitro study without cellular or animal data. Whether the improved binding potency translates to improved cellular activity is unknown. The dibromomaleimide staple is one of many stapling chemistries; results may differ with other approaches. Molecular dynamics simulations are models, not direct observations.
How to read the evidence
Moderate evidence from biophysical studies. Clear mechanistic finding but tested only on one protein-protein interaction in vitro.
When this study was published
Published in 2020. Stapled peptide design has continued to evolve, incorporating insights from studies like this.
The bigger picture
Protein-protein interactions drive cancer and inflammation but are hard to drug with small molecules. Stapled peptides are a leading strategy. This study changes how researchers design them — focusing on bound-state properties rather than solution-state pre-organization.
Questions still open
- Does this bound-state mechanism apply to stapled peptides targeting other protein interactions?
- Could computational tools predict bound-state helicity to guide design?
- What other stapling chemistries produce similar bound-state enhancement?
Common questions
What is peptide stapling?
Why does this matter for cancer drug development?
Read the original research
Stapled Peptides as HIF-1α/p300 Inhibitors: Helicity Enhancement in the Bound State Increases Inhibitory Potency.
Chemistry (Weinheim an der Bergstrasse, Germany), 26(34), 7638-7646
Citation
Hetherington, Kristina; Hegedus, Zsofia; Edwards, Thomas A; Sessions, Richard B; Nelson, Adam; Wilson, Andrew J. (2020). Stapled Peptides as HIF-1α/p300 Inhibitors: Helicity Enhancement in the Bound State Increases Inhibitory Potency.. Chemistry (Weinheim an der Bergstrasse, Germany), 26(34), 7638-7646. https://doi.org/10.1002/chem.202000417